Direction-finding system



Aug. 17, 1943. KARL-GEORG HOLSTEN 2,325,945

DIRECTION-FINDING SYSTEM Filed July 5, 1941 FIGJ.

INVENTOR. "/fI/Pl. 650/96 //04s7/v ATTORJYE': c

Patented Aug. 17, i943 UNITED 1 STATES". PATENT oF IcE 5 DIRECTION-FINDING SYSTEM Karl-Georg Holsten, Berlin, Germany; vested in the Alien Property Custodian Application July 5, 1941, Serial No. Y In Germany March 2, 1940 3 Claims.

In direction finding arrangements of the kind comprising a directional antenna system and a non-directional one it is well known to take the voltage for the non-directional antenna from the directional system itself, that is, without the aid of an auxiliary antenna. For instance, in an Adcock system the middle of the. field coils is tapped to such end. This mode, however, has the disadvantage that care must be taken to find out. the exact position of the center points of the field coils and further, that additional inductances arise in the antenna line since the turns of the field coils are not perfectly coupled together at their ends, the leakage inductance of the field coils thus acting on the antenna voltage. This leakage inductance in most cases entails an appreciable additional phase rotation which is the more precarious the more the operating conditions of the system entail resonance of the antenna structure, as is often the case especially with short waves. 7

All these drawbacks are overcome by the present invention. According to the invention the field coils of a goniometer or the coupling coils of loop antennae used with goniometers, as the case may be, are each associated with a doublewound choke connected in parallel with the respective coil and joined at its center point to the non-directional antenna terminal.

The invention is also concerned with a novel construction of such double-wound chokes, as will be understood from the following description and the accompanying drawing, in which Y Fig. l is a partially perspective diagrammatic view of one embodiment of the invention, Fig.2 is a diagrammatic view showing one form of the double-wound chokes.

' The arrangement illustrated in Fig. 1 comprises an Adcock antenna system of known form in which four radiators arranged in the form of a square are coupled to field coils F1 and F2, which are in turn coupled to search coil S. Such antennae are commonly used for direction finders although the principles thereof also apply to transmitters. To obtain a uni-directional pattern the antenna efiect of the system is used. Chokes D consisting of coils wound in opposed relation are provided in shunt to each of the field coils F1 and F2. The center points of chokes D are interconnected for connection to the usual sense" antenna terminal of the system.

The chokes D, one of which is represented in Fig. 2 by way of example, are each composed of,

two coiled wires joined together at opposite ends to form a tap for the non-directional antenna voltage, while the other ends are connected to thelrespectivo field coil in'parallel with each other. The construction of the chokes should eluding a choke coil arragement associated with be such that the inductance in the longitudinal direction is very small while in the transverse direction it is very great, that is, the two coiled wires have a very large inductance therethrough between the ends thereof which are not joined together, while these wires have a very small inductance from said unjoined ends to the joined 7 ends over the path provided for transmission of the non-directional antenna voltage.

The inductance of the, chokes D is made to be high eomparedwith that of the coils F1, F2. For instance, the inductance of D may be ten times that of F1, F2.

It will be seen that the construction of the goniometer need not be changed in any way, this being important especially in the case'of shortwave goniometers, the conductors employed in these having to be located in distinct positions. The novel arrangement also acts to protect the non-directional antenna voltage from any additional phase rotation which otherwise may be causedby the leakage inductance of the field' coils. I

What is claimed is 1 1. In a direction findingsystem having a directional antenna system, and directional coil elements operatively associated with said directional antenna system for deriving therefrom a directional efifect, the combination of means for deriving from said directional antenna system a non-directional antenna effect, said means ineach said directional coil element, each said choke coil arrangement including two coiled" wires joined directly together at one end of each'wire and um'oined at the other end thereof, said wires having a very large inductance therethrough between said unjoined ends while having a very small inductance from said unjoined ends to said joined ends, and a conductor for said non-directional eiiect connected to said joined ends of each said choke coil arrangement, said unioined ends of each said choke coil arrangement being connected in parallel across the respectiveone of said directional coil elements associated'with said choke coil arrangement.

2. A direction finding system according to claim 1, wherein said directional coil elements are the field coils of a goniometer.

3. A direction finding system according to claim 1, wherein said directional coil elements are the field coils of a, goniometer, and the inductance of each said choke coil arrangement between said KARL-GEORG HOLS'I'EN. 

